Backfiring |
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Backfiring |
BfloRandy |
Apr 10 2017, 06:02 PM
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#1
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Dimwit Extraordinaire Group: Members Posts: 66 Joined: 20-September 14 From: Buffalo, NY Member No.: 17,927 Region Association: North East States |
Happy Spring, aka fix your car so you can drive it all summer!
Having an issue tuning my Weber 40's. The car does run, and idles quite well, sounds smooth and even. If I rev beyond 3k, I get backfires. Starts fine too. Ordinarily I would assume it's a simple matter of resetting and resyncing. Passenger side carb is as it always has been, fine. Mix adjustment screws work normally, idle adjustment also. I see the squirt from the accelerator jets. Driver side, not so much. It's getting gas. For some reason, the mix screws have little to no effect. This is on BOTH cylinders. The only time I notice any change in the engine's sound is if I back them way way out, then I get backfiring and carb throat sneezing. Otherwise, I can have them set just about anywhere, including fully seated, and there is no difference. I've pulled the carb off, (three times now) torn it down and blown everything out a couple of times already. I did see some blockage in the idle jets and mains before I blew them out. I also noticed that I didn't see any squirt from the accelerator jets. I tore it down again, and fiddled with the pump (new last spring) and reassembled it. Accel jets now appear to work normally. It doesn't at all help that my kids decided to reorganize a ton of things, and I now can't find my Weber manual. (IMG:style_emoticons/default/chair.gif) Can anyone help? Thanks! |
BfloRandy |
Apr 26 2017, 05:26 PM
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#2
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Dimwit Extraordinaire Group: Members Posts: 66 Joined: 20-September 14 From: Buffalo, NY Member No.: 17,927 Region Association: North East States |
Complete update and status...
Since I neglected to mention this previously - 75 2.0, dual IDF 40's. New plugs, rotor, cap, condenser and points. Checked wiring for faults. Found none. Wires, coil and dizzy new last spring. Dwell is at 46.7 degrees. Timing set to 34 degrees BTDC at 3200 rpm, as per PP article on timing for carbs. Had it at 27, but thought I'd try the new number as it came from PP. Now the idle sits at 1700 !!! Throttle valves apparently not fully closing, as I can get the idle to drop a bit if I pull up (kinda hard) on the droplinks, whether connected to the linkage bar or not. Therefore, not caused by the linkage. Odd thing is that when I had them off the car, I checked this specifically and was unable to get ANY movement from them. I can drop the idle down to a normal range if I retard the advance enough, but then the timing is way off. Still getting popping and/or backfiring when revved over 3k. Sprayed carb cleaner around areas where there are gaskets that could be causing a vac leak. Nothing found. So, it appears that I have two separate issues. High idle and backfiring. Valve adjustment (again) is next, I think. Any other ideas??? At my wit's end... (IMG:style_emoticons/default/mad.gif) |
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